(1) Field of the Invention
The present invention relates to a method of improving the strength and failure resistance of single crystal gas turbine components and to a turbine engine component formed thereby.
(2) Prior Art
Single crystal nickel-based superalloys consist of cuboidal precipitates (known as γ′ particles) separated by channels of γ-matrix as shown in FIG. 1. Effectively, the γ′ particles and the γ-matrix act as a composite material, where the γ′ particles provide strength, while the γ-matrix provides ductility. Under load, the γ′ particles tend to coalesce into layers (known as platens). This behavior is shown in FIG. 2. Tensile loading produces layers of γ′ that are perpendicular to the applied stress σ, (N-type rafts) while compressive loading produces layers of γ′ that are parallel to the applied stress σ (P-type rafts) for negative lattice mismatch. These layered structures are weaker than the original structure and tend to crack at the interface of the γ′ platens and the γ-matrix, with cracks propagating along the platens. This behavior is schematically shown in FIG. 3. Under continued loading, these cracks propagate and join with others, eventually resulting in material failure.